The sizes that are used to draw non-pixmap icons on
a icon-drawing-view in a
chart-or-plot. The value
should be a sequence (list or vector) of positive integers. The
default value is a list of the number 4.

Each non-pixmap icon is drawn centered about its data point and
extending outward from this center point by (approximately) the
specified number of pixels in each direction. The size value can
therefore be thought of as the "radius" of the icon. An exception is
that for the built-in :dot icon, the value
indicates the "diameter" of the icon (though
the :dot icon is actually square). This is to
allow dots that are 1 (or 3 etc.) pixels across, especially in a
plot-widget where small
dots may be needed.

If this property value is nil, then all
non-pixmap icons are drawn with a size of 6. Otherwise, the first
object in the chart-widget's sequence of chart-objects is drawn with the first icon size,
the second object with the second size, and so on. If there are fewer
sizes in the list than there are chart-objects, then the drawing code will cycle
back through the list of sizes as needed.

This property is used only when the draw-icons property is true and
the icon-images property
contains one or more non-pixmap elements.